Compared to the article font-size of 15.2px editor text is too small to provide a convenient UX.
===== Steps to Reproduce:
Compare text in the editor to sidebar links, latter is the same as article text.
WTE / WTE2010:
1. https://www.mediawiki.org/w/index.php?title=2017_wikitext_editor&action=edit&useskin=timeless
WTE2017:
1. [[ https://www.mediawiki.org/wiki/Special:Preferences#mw-prefsection-betafeatures | Enable ]] "New wikitext mode"
1. https://www.mediawiki.org/wiki/2017_wikitext_editor?veaction=editsource&useskin=timeless
===== Reason
For historical reasons related to browsers implicitly setting monospace elements' font-size to something //around// 13px (inconsistently, ofc):
{T182320} sets the font-size to 13px for all skins, all editors, also when using non-monospace font.
Not an issue (not noticeable) in Vector (body: 14px), MonoBook (12.7px), Modern (13px).
Minerva avoids this by resetting paragraphs' (not the editor's) font-size to 16px.
===== Fix
Reset (inherit) default page font-size in editors (in Timeless).
== Screenshots
Bad vs Good:
| {F31621703} | {F31621704}
Before and after fix:
| {F31674546} | {F31674547}